1. Field of the Invention
The present invention relates generally to medical methods and devices. More particularly, the present invention relates to medical methods and kits for injecting pharmaceutical agents into tissue surrounding blood vessels and other body lumens.
Coronary artery disease is the leading cause of death and morbidity in the United States and other western societies. In particular, atherosclerosis in the coronary arteries can cause myocardial infarction, commonly referred to as a heart attack, which can be immediately fatal or, even if survived, can cause damage to the heart which can incapacitate the patient. Other coronary diseases which cause death and incapacitation include congestive heart failure, vulnerable or unstable plaque, and cardiac arrhythmias. In addition to coronary artery disease, diseases of the peripheral vasculature can also be fatal or incapacitating. Vascular occlusions, blood clots and thrombus may occlude peripheral blood flow, leading to tissue and organ necrosis. Deep vein thrombosis in the legs can, in the worst cases, require amputation. Clots in the carotid artery can embolize and travel to the brain, potentially causing ischemic stroke.
While coronary artery bypass surgery is an effective treatment for stenosed arteries resulting from atherosclerosis and other causes, it is a highly invasive procedure which is also expensive and which requires substantial hospital and recovery time. Percutaneous transluminal coronary angioplasty (PTCA), commonly referred to as balloon angioplasty, is less invasive, less traumatic, and significantly less expensive than bypass surgery. Until recently, however, balloon angioplasty has not been considered to be as effective a treatment as bypass surgery. The effectiveness of balloon angioplasty, however, has improved significantly with the introduction of stenting which involves the placement of a scaffold structure within the artery which has been treated by balloon angioplasty. The stent inhibits abrupt reclosure of the artery and has some benefit in reducing subsequent restenosis resulting from hyperplasia.
Despite such improvement, patients who have undergone angioplasty procedures with subsequent stenting still suffer from a high incidence of restenosis resulting from hyperplasia. Very recently, however, experimental trials have demonstrated that the implanting of stents which have been coated with anti-proliferative drugs can significantly reduce the occurrence of hyperplasia, promising to make combined angioplasty and stenting a viable alternative to bypass surgery.
As an alternative to stent-based luminal drug delivery, the direct delivery of drug into vascular and other luminal walls has been proposed. For some time, the use of intravascular catheters having porous balloons, spaced-apart isolation balloons, expandable sleeves, and the like, have been used for releasing drugs into the inner surface of the endothelial wall of blood vessels.
Of particular interest to the present invention, catheters carrying microneedles capable of delivering therapeutic and other agents deep into the adventitial layer surrounding blood vessel lumens have been described in co-pending application Ser. No. 09/961,080, filed on Sep. 20, 2001, and Ser. No. 09/961,079, also filed on Sep. 20, 2001, both applications having common inventorship with but different assignment than the present application, the full disclosures of which are incorporated herein by reference.
The designs described in the copending applications have numerous advantages. The microneedles are delivered in a direction which is substantially perpendicular to the axis of the catheter, thus maximizing the depth of needle penetration into the wall and reducing trauma and injury. Moreover, by locating the needles on the exterior of an expanding involuted surface, the needles can be injected into tissue fully up to their point of attachment to the catheter, further maximizing the needle penetration depth which may be achieved. In some instances, however, it may be desirable to employ even longer needles than may be deployed using the catheter designs disclosed in these two copending applications.
For these reasons, it would be desirable to provide additional and improved devices and methods for the intraluminal delivery of pharmaceutical agents for the treatment of a variety of diseases. In particular, it would be desirable to provide improved needle injection catheters and methods for their use which are able to achieve a wide range of tissue injection depths, from very shallow to very deep including depths greater than the available width of the needle injection catheter being used. It would be further desirable to provide such devices and methods where the needle may be injected into tissue using a driver or other motive force located very close to the point of tissue injection to maximize the penetration force achieved. In particular, it would be desirable to avoid the need to push at the proximal end of the needle which is being injected through a catheter in order to advance the distal end into tissue. At least some of these objectives will be met by the inventions described hereinbelow.
2. Description of the Background Art
U.S. patent application Ser. Nos. 09/961,079 and 09/961,080, both filed on Sep. 20, 2001, and both having common inventorship with but different assignment than the present application, describe microneedle catheters. U.S. Pat. No. 4,578,061, describes needle injection catheters having deflectable, axially advanceable needles. U.S. Pat. No. 5,538,504, describes a needle injection catheter having a transversely oriented needle that is laterally advanced by a balloon driver. Also of interest are U.S. Pat. Nos. 6,319,230; 6,283,951; 6,283,947; 6,004,295; 5,419,777; and 5,354,279.